Some subjects need nutrition, either as a supplement, or as a complete nutrition, in the smallest volume of liquid, that is still effective for its intended purpose.
These subjects can be cachectic patients or persons suffering from end-stage AIDS, cancer or cancer treatment, severe pulmonary diseases like COPD (chronic obstructive pulmonary disease), tuberculosis and other infection diseases or persons that experienced severe surgery or trauma like burns. Furthermore, persons suffering from disorders in the throat or mouth such as oesophageal cancer or stomatitis and persons having problems with swallowing like dysphagic persons, require special liquid, low-volume nutrition. Also, persons just suffering from reduced appetite or loss of taste, will benefit from low-volume, preferably liquid, food.
These subjects can also be elderly persons, in particular frail elderly and elderly at risk of becoming frail. In this regard, although an elderly person's energy needs may be reduced, their ability to consume products may also be diminished. For example, they may have difficulty consuming a product due to, e.g., swallowing difficulties, or due the too large amount of product they need to consume to meet the daily intake of nutrients. Hence, compliance is not optimal, and often, the intake is suboptimal, leading to suboptimal nourishment, and in the end, to malnutrition.
These subjects can also be sportsmen (male or female), as a sportsman also may benefit from a concentrated protein drink.
Due to a prerequisite of at least six months of shelf life in general, preferably at least 12 months, whey protein compositions need to undergo some sort of sterilization treatment in order to reduce the number of or remove possible pathogens, for instance spores, bacteria and other microorganisms, which cause spoilage of the protein composition, preferably by using heat (sterilization, pasteurization), radiation (UV-treatment), or filtration methods (ultrafiltration, diafiltration, nanofiltration). Preferred sterilization treatments include heat treatments at high temperatures for a short period, such as using a UHT (Ultra High Temperature) treatment. However, when subjecting whey proteins to heat, whey proteins are rapidly denaturated whereby the whey protein globular structure enfolds, and at a pH between 3 and 7 may form agglomerates and macrostructures, which are visible as a haze or turbidity. Eventually, the agglomerates will sediment and the nutritional composition will become unacceptable for further consumption. The use of acid whey (i.e. whey with a pH<7, preferably with a pH between 3 and 5), either obtained from an acid whey process (also known as “sour whey”), or by acidification of whey (acidified whey), obtained from acidifying sour whey or sweet whey by e.g. the addition of an acid such as phosphoric acid, is preferred because acid whey is less prone to pathogens and hence, only needs a mild sterilization treatment by heat, such as a pasteurization or UHT treatment. Furthermore, an acid whey protein composition has a more preferred taste and smell than a neutral (pH about 7) whey protein composition.
The aforementioned groups of subjects may be sensitive to food consistency and to the organoleptic properties of an acid composition comprising a high amount of non-hydrolysed globular proteins, such as whey proteins, such as, for instance viscosity, taste, smell, colour and mouth feel, in particular astringency.
Acid whey protein solutions elicit an astringent taste sensation in the mouth, irrespective of the source of whey (WPI, WPC and others). Although the exact mechanism of astringency by whey proteins is not known, it has been published (Astringency of Bovine Milk Whey Protein, H. Sano, T. Egashira, Y. Kinekawa, and N. Kitabatake, J. Dairy Sci. 88:2312-2317) that most of the whey protein precipitates in the mouth at about pH 5. When an acid WPI solution (pH 3.5) is placed in the oral cavity, the acid solution is mixed with saliva (pH of about 7), causing the pH of the whey protein solution to increase but to remain at a pH<5. At this pH (near the iso-electric point of the whey protein), whey protein would precipitate in the mouth. This precipitate is formed in the oral cavity and would induce astringency in a similar way to the complex precipitation formed by salivary protein and polyphenolic compounds, as can be found in wine, green tea and some fruits.
Furthermore, it was established that astringency increases with increasing whey concentrations and shows a maximum at pH 3. This makes astringency to become a real taste problem in nutritional compositions having a high amount of whey and an acidic pH. The problem is in particular apparent at an acid pH of about 3, in particular at a pH between 3 and 5.
It is further contemplated that the presence of divalent metal cations, such as magnesium and calcium—both important nutrients—may contribute to astringency. Further, it is contemplated that the presence of divalent metal cations, in particular calcium may adversely affect the solubility of whey protein and/or adversely affect viscosity of a liquid comprising whey protein, and/or adversely affect the shelf life, in particular in case the whey protein concentration is relatively high, or the liquid is heat-treated.
In view of expected problems with respect to organoleptic properties, in particular astringency, protein solubility and/or controlling viscosity, the skilled person would therefore not consider to provide a sterilized liquid or semi-solid acid enteral composition comprising a high amount of non-hydrolysed globular proteins, such as whey, fat, and a high amount of divalent metal cation, as he would not expect to be able to provide such as product with satisfactory properties for the consumer.
Therefore, a problem underlying the present invention is how to provide a sterilized liquid or semi-solid acid enteral composition comprising a high amount of non-hydrolysed globular proteins, such as whey, fat, and a high amount of divalent metal cations, such as calcium and magnesium, and having satisfactory properties, in particular satisfactory shelf life and satisfactory organoleptic properties, for providing nutrition, either as a supplement, or as a complete nutrition.
In particular, a problem underlying the invention is how to provide such a product with a satisfactory shelf life and no or a low astringency and/or no or a low sandiness
More in particular, a problem underlying the invention is how to provide a sterilized liquid or semi-solid acid enteral composition comprising a high amount of non-hydrolysed globular proteins, such as whey, fat, and a high amount of divalent metal cation in a relatively small volume of liquid, whilst supporting nutrition and well-being in the different subject groups mentioned above.
The inventors have now found that such a problem is solved by preparing a sterilized liquid or semi-solid acid enteral composition in a specific way, namely using a method for producing said composition, comprising at least a direct steam injection (DSI) step, whereby the DSI is used for non-sterilizing purposes. Thus, the present invention makes it possible to provide the specific composition as defined herein below and in the claims, as an industrially applicable composition.